1. Field of the Invention
The present invention generally relates to a retractable running board for a vehicle such as a pick up truck or a van.
2. Description of the Related Art
Running boards are commonly found on pick up trucks, vans, sport utility vehicles and other types of automobiles. Running boards serve as a step, particularly on vehicles where the vehicle has a high clearance, providing easier access to the vehicle.
It has been found that it can be advantageous to have a running board which retracts when not in use. For example, a fixed running board""s lateral extension can create a risk of damage to the running board and the vehicle during travel through a narrow passage. Retracting the running board reduces this risk. A retracted running board can also improve the aerodynamics of a vehicle, and thus the fuel efficiency of the vehicle.
Several different types of retractable running boards are known in the art. U.S. Pat. No. 3,887,217 to Thomas discloses a retractable step which is powered by a reversible motor and is clamped to the frame of the vehicle via a vertical base. Two inwardly-angled outer frame members depend respectively from the opposite ends of the step and converge at the vertical base, while a third frame member depends from the center of the step and joins the convergence of the outer frame members at the vertical frame. The third frame member is engaged by the motor, also mounted to the vertical base. While providing a retractable step, Thomas suffers from decreased fore and aft stability as the depth of the step is increased, due to the single linkage of the frame members to the inner edge of the step. Further, the Thomas mechanism must be clamped to the vehicle, which can create difficulties during installation, and risks the possibility of improper installation. Thomas also requires clamping to a vehicle frame, which is not always possible on modem uni-body frame less vehicles. Finally, as shown in FIG. 1 of Thomas, the retractable running board in Thomas can actually decrease the vehicle ground clearance, as a portion of the outer frame members swing underneath the frame in the retracted position.
U.S. Pat. No. 5,137,294 to Martin discloses a step assembly for vehicles which simply raises and lowers the step by pivoting the step about an axis perpendicular to the longitudinal horizontal axis of the vehicle. A spring mechanically biases the step into a raised position, while a cable mechanically links the door to the step, such that opening the door lowers the step, while closing the door raises the step. This arrangement is disadvantageous because an interference between the step and the ground can prevent the door from being opened, thus creating a safety hazard. Further, the spring in Martin increases the effort required to open the door, as the spring biases the step into a closed position, it also biases the door towards a closed position. Also, the step in Martin lacks fore and aft support, thus decreasing the stability of the step as the step depth is increased. Finally, the step in Martin does not laterally retract towards the body of the vehicle, thus exposing the step to damage during driving through certain narrow passageways.
U.S. Pat. No. 5,697,626 to McDaniel et al. discloses a vehicle running board which raises when the vehicle door is closed, and lowers when the vehicle door is opened. The running board in McDaniel comprises first and second outer telescoping members. Each member is mounted by its distal end to the vehicle, while a spring urges the telescoping portion of each member into a retracted position. A central longitudinal running board member is pivotally mounted between the outer members. A linkage can be actuated to swing the outer members downwards and telescope outwards, thereby lowering the running board. McDaniel does not retract the step, but only raises it, thus exposing the running board to damage during vehicle operation through narrow passages. Further, the lack of central support in the running board can result in deflection of the board when subjected to heavier weights.
It will thus be apparent that improvements to the art of retractable running boards is desirable.
Accordingly, it is an object of the present invention to provide a novel retractable running board which obviates or mitigates at least one of the disadvantages of the prior art.
In a first broad aspect of the present invention, there is provided a retractable running board for a vehicle, wherein the running board comprises a bracket for attachment to the vehicle, a step for assisting entrance to and exit from the vehicle and a parallelogram linkage connecting the step to the bracket. The step is moveable between a retracted position under the vehicle and an extended position extending from the vehicle. In order to move the step, a motor is provided.
According to another aspect of the invention, there is provided a retractable running board assembly which has a step, at least two support arms, at least two mounting brackets, at least two pairs of parallel links and a drive. The step has an elongate stepping surface extending generally parallel to a longitudinal axis of a vehicle on which the running board assembly is mounted. The support arms are mounted to the step. The mounting brackets are connected to an underside of the vehicle. The parallel links are pivotally connected between each of the support arms and the mounting brackets. The drive effects movement of the step between an extended outboard position and a retracted inboard position.